Solid fuel burning furnace



Nov. 26, 1940. EM N- 2,222,893

SOLID FUEL BURNING FURNACE Filed Nov. 1a, 1936 2 Sheets-Sheet 1 r 1" K /K INVENTOR 15 #Hueo ALLEMANN Y W. W TM Arne/vs Ys Nov. 2 1940.

H. ALLEMANN SOLID FUEL BURNING FURNACE Filed Nov. 18, 1936 2 Sheets-Sheet 2 INVENToR Huso ALLEMANN BY wfi fim AT ORNEYS Patented Nov. 26, 1940 EED STATES Application November 18, 1936, Serial No. 111,529

' In Switzerland November 25, 1935 2 Claims. (01. 12e 112) The present invention relates to a furnace for solid fuel.

The principal object of the invention is to provide, in addition to an efficient utilization of heat, the possibility of diminishing the emission of heat suddenly from a maximum to Zero and of changing the generation of heat nearly to naught and to provide that even after a day's stop the emission of heat may be raised suddenly to the maximum.

The annexed drawings illustrate an embodiment of the invention. In the drawings:

Fig. 1 is a longitudinal section on lineI-I in Fig. 3,

Fig. 2 a sectional front elevation with the front wall removed,

Fig. 3 a plan view of a horizontal section on line III-III in Fig. 2,

Fig. 4 a plan of the furnace with the cover removed.

According to the drawings a cylindrical furnace 2 and a recuperator of heat 3 are carried by a bottom plate l forming a partition wall, inside of a fireproof and hermetically sealed brick chamber l. The furnace proper 2 comprises a sheet iron envelope 1 inside of which a grate 6 is arranged and combined with a square box forming the casing of a thermostat. The grate and square box are carried by a cylindrical case 9' supported by the bed plate 4 and forming the ash pit of the furnace. The cylindrical fire box 8 is constructed of refractory bricks and surrounded by insulating material In filling the space between the envelope 7 and the walls of the ash pit and fire box. This fire box supports inside of a funned-like extension, a refractory ring 8 having passages 8 between said extension and ring for the gases of combustion. An iron cylinder ll serving as a chute for the solid fuel is carried by said ring 8 and is extended to the outside of the brick chamber where it is closed by a cover l2. The hollow space between envelope 1 and chute H is covered by a sheet iron collar 13 and forms a flue from which the combustion gases are led through a neck l3 into the recuperator 3. The latter is formed of a central tube I! closed by a cover I1 and arranged centrally inside of a hollow cylinder M. This cylinder is formed with a number of annular ribs l4 and partition walls I4 provided with passage openings I4 and the gases are led from theneck l3 in several manifold windings around the central tube I! to be discharged into a smoke flue 15 arranged underneath the bottom plate 4 and provided with a cleaning door l5. From here the gases may escape through a vertical chimney tube It. The hollow cylinder M is provided on its outside with longitudinal ribs I4 which are surrounded by an envelope 3. Thereby an air jacket is formed between envelope l8 and cylin- 5 der l4 constituting the sole communication between the inside of a hood 20 covering the envelope l8 and the fresh air admission chamber l9 formed beneath the bottom plate 4. Hood 2G is hermetically joined to the envelope l8 and opens into the hub of a blower M which is adapted to deliver the hot air from between the ribs l4 into the space I" surrounding the envelopes l and I8 of the furnace and the recuperator. The blower 21 is located just beneath the bedplate 22' of an electric motor 22 in an opening of the top plate I of the brick chamber and is operated by this motor. In the space i" the hot air flows from the periphery of the blower around the baffle plate 23, made accessible through the cleaning hole 2'3, into the vertical air flue 38 in a corner of the brick chamber. The cleaning hole 24 is covered by a loose plate which serves as a safety escape for the heated air in case of the outlet 38 being choked.

The square box 5 enclosing the thermostat is provided with lateral teeth-like extensions 5 forming part of the grate. A two armed bracket 26 pivoted to a pin carries on one arm said thermostat. A flexible steel band 21 of the thermostat is attached to one arm of this bracket and with its other arm to a brass rod 28 which rests with its other end against a rotatable pin held in a slot of said bracket. An adjusting rod 29 introduced through the cover plate I of the brick chamber and crossing the upper wall of box 5 bears on the bracket 26 to counterbalance the thermostat. This rod has a weight 30 screwed to its bottom, which may be adjusted so as to limit the effect upon said bracket, by its contact with the box. Underneath this box, cast to it and opening into the ash pit is anair admission box 5 The air admitting valve seat is provided in its bottom wall and cooperates witha valve disc 32 having its stem 3! guided in an eye 5 of box 5 and supported by the brass rod 28 which is engaged into a lateral notch of said valve stem. By this arrangement valve 32 will follow all swingings of the end of the thermostat. But the valve stem 3| is also hinged to an arm 35 fast to a shaft 33 to the end of which is fixed a damper 34 controlling the inlet into a vertical chimney tube l6.

A pipe 36 bent at its upper end in the direction of the air current produced by the blower is provided with a handle 36' projecting over the cover plate I and is held loose in a nipple of box 5. This box 5 is provided at its left end with a flap 3! arranged to let any air pressure inside of the box 5 escape but to prevent entry of any air from the outside. In the air chimney 38 shown with dotted lines in Fig. 3 a flap Valve 39 (see Fig. 1) is held by means of silk cord 4! attached to an arm 40 rigidly fast to said valve in its open position. Should an open flame reach said silk cord it would be consumed and let the valve drop, whereby said fire would become choked.

The thermostat 25, 25, 21, 23 is made so sensitive that at a difference of temperature of about 50 the valves 32 and 34 are opened or closed completely, while the adjustment of adjusting rod 29 is such that the valves are closed at a glowing heat of 800. By the simultaneous adjusting of both valves it will be possible to render the chimney draught completely automatically adjustable. Since the extensions 5 are in direct contact with the fire, the glow of the fire can at a stop of the operation of the whole arrangement be kept so constant, that it will never be extinguished and upon starting of the blower will work again with full effect. The insulating of the furnace reduces its radiation to a minimum and therefore the plant Will consume very little combustible during the stops. As soon as the blower begins to run, some air will be blown through the pipe 38 and strike the thermostat and lift the flap 3'! leading into the free space of the brick chamber. Thereby the thermostat, which during the stop has assumed nearly the temperature of the fire, will be cooled. This is the purpose of opening valves 32, 34. A certain pressure is produced by the blower in the brick chamber so that the admission of air through the opening of the valve 32 and neck 52 into the fire is increased and thereby also the development of heat is increased.

In order to adapt the development of heat to the state of the atmosphere the pipe 36 may be turned more or less into the air current produced by the blower so that the cooling of the thermostat will also change in a corresponding manner.

If the temperature in the dwelling rooms is very low, the thermostat, while maintaining the same adjustment of the pipe 36, will be further cooled and at a higher temperature of the dwelling the room will be less cooled, so that at a low temperature the furnace will develop more heat and at a higher temperature less heat.

What I claim is:

1. In a fluid heating furnace, a fire-box comprising refractory material for solid fuel, a grate, a chamber above the fire-box for receiving hot combustion gases from the fire-box, a duct for supplying combustion supporting air to the firebox, a valve in said duct, a thermostat for controlling said valve mounted on the grate for direct exposure to the temperatures in the fire-box, a fluid-containing jacket surrounding said chamber, fire-box and grate, the fluid therein being in heat exchange relation with said chamber, and insulation surrounding said fire-box and grate for preventing the cooling of the contents of said fire-box by the fluid in said jacket.

2. In a fluid heating furnace, a fire-box comprising refractory material for solid fuel, a grate, a chamber above the fire-box for receiving hot combustion gases from the fire-box, said chamber having walls of heat-conducting material for transferring heat from hot gases in said chamberto a medium surrounding said chamber and fire-box, a duct for supplying combustion supporting air to the fire-box, a valve in said duct, a thermostat for controlling said valve mounted immediately adjacent the fire-box for direct exposure to the temperatures in the fire-box, and insulation surrounding said fire-box and grate for preventing the medium surrounding said chamber and fire-box from cooling the fire-box and grate.

HUGO ALLEMANN. 

